U.S. patent number 6,516,197 [Application Number 09/272,693] was granted by the patent office on 2003-02-04 for system and method for reporting the number and/or duration of positioning requests for terminal-based location calculation.
This patent grant is currently assigned to Ericsson Inc.. Invention is credited to David Boltz, Theodore Havinis.
United States Patent |
6,516,197 |
Havinis , et al. |
February 4, 2003 |
System and method for reporting the number and/or duration of
positioning requests for terminal-based location calculation
Abstract
A telecommunications system and method is disclosed for
requiring a mobile station (MS) to notify the network of the number
and/or duration of positionings performed by the MS. A service
program or API (Application Program Interface), e.g., JAVA program,
which is responsible for collecting information regarding the
requests for location information, is either included in a
Subscriber Identity Module (SIM) card, or other memory, of the MS,
or downloaded to the SIM card in the MS. As a result of performing
a location calculation, the API within the MS initiates a mobile
originated reporting Short Message Service (SMS) or Unstructured
Supplementary Service Data (USSD) message to the serving network,
which includes a time stamp of the time and date the positioning
request was received, the number and/or duration of the
positioning(s) and the final location of MS.
Inventors: |
Havinis; Theodore (Plano,
TX), Boltz; David (Garland, TX) |
Assignee: |
Ericsson Inc. (Research
Triangle Park, NC)
|
Family
ID: |
23040880 |
Appl.
No.: |
09/272,693 |
Filed: |
March 18, 1999 |
Current U.S.
Class: |
455/456.1;
455/466 |
Current CPC
Class: |
H04W
4/029 (20180201); H04W 4/02 (20130101) |
Current International
Class: |
H04Q
7/22 (20060101); H04Q 007/20 () |
Field of
Search: |
;455/456,404,435,412,413,414,433,436,553,457 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Chin; Vivian
Assistant Examiner: Moore; James K
Attorney, Agent or Firm: Jenkens & Gilchrist, P.C.
Claims
What is claimed is:
1. A mobile station for reporting positioning information to a
network in wireless communication with said mobile station,
comprising: a transceiver unit for receiving a positioning request
for said mobile station and sending a reporting message including
at least said positioning information to said network; a
positioning measurement module connected to said transceiver unit
for obtaining at least one positioning measurement for said mobile
station; a location calculation module for receiving said at least
one positioning measurement for said positioning measurement module
and calculating at least one location information identifying the
location of said mobile station within said network, using said at
least one positioning measurement; and a reporting module for
receiving said location information from said location calculation
module and initiating said reporting message towards said
transceiver unit, said positioning information comprising the
number of said at least one location information calculated by said
mobile station and/or the duration of time over which all of said
at least one location information were calculated.
2. The mobile station of claim 1, further comprising: a memory for
storing said positioning information and each said calculated
location information until said reporting module initiates said
reporting message.
3. The mobile station of claim 2, wherein said reporting module has
a reporting frequency stored therein, said positioning information
and each said calculated location information being stored in said
memory until said reporting frequency indicates that said reporting
module should initiate said reporting message.
4. The mobile station of claim 2, wherein said reporting message
further includes a last calculated one of said at least one
location information.
5. The mobile station of claim 1, wherein said reporting message
further comprises a time stamp indicating the date and time that
said positioning request was received by said mobile station.
6. The mobile station of claim 1, wherein said reporting message is
a Short Message Service message.
7. The mobile station of claim 1, wherein said reporting message is
an Unstructured Supplementary Service Data message.
8. The mobile station of claim 1, wherein said reporting message is
a Wireless Application Part interface.
9. The mobile station of claim 1, wherein said positioning
measurement module and said location calculation module comprise a
Global Positioning System transceiver unit.
10. The mobile station of claim 1, wherein said at least one
positioning measurement is an enhanced-observed time difference
measurement.
11. A method for reporting positioning information by a mobile
station to a network in wireless communication with said mobile
station, comprising the steps of: receiving, by said mobile
station, a positioning request for said mobile station; obtaining
at least one positioning measurement by said mobile station;
calculating, by said mobile station, at least one location
information identifying the location of said mobile station within
said network, using said at least one positioning measurement; and
sending, by said mobile station, a reporting message, including at
least said positioning information, to said network, said
positioning information comprising the number of said at least one
location information and/or the duration of time over which all of
said at least one location information were calculated.
12. The method of claim 11, further comprising the step of:
storing, within a memory within the mobile station, said
positioning information and each said calculated location
information.
13. The method of claim 12, wherein said step of sending further
comprises the steps of: sending said reporting message, including
at least said positioning information and a last calculated one of
said at least one location information, to said network.
14. The method of claim 11, wherein said step of sending further
comprises the step of: sending said reporting message, including at
least said positioning information and a time stamp indicating the
date and time that said positioning request was received by said
mobile station, to said network.
15. The method of claim 11, wherein said step of obtaining further
comprises the step of: obtaining at least one Global Positioning
System positioning measurement.
16. The method of claim 11, wherein said step of obtaining further
comprises the step of: obtaining at least one enhanced-observed
time difference positioning measurement.
Description
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to telecommunications
systems and methods for positioning a mobile station within a
cellular network, and specifically to reporting the number and/or
duration of positioning requests performed by a mobile station.
2. Background and Objects of the Present Invention
Cellular telecommunications is one of the fastest growing and most
demanding telecommunications applications. Today it represents a
large and continuously increasing percentage of all new telephone
subscriptions around the world. A standardization group, European
Telecommunications Standards Institute (ETSI), was established in
1982 to formulate the specifications for the Global System for
Mobile Communication (GSM) digital mobile cellular radio
system.
With reference now to FIG. 1 of the drawings, there is illustrated
a GSM Public Land Mobile Network (PLMN), such as cellular network
10, which in turn is composed of a plurality of areas 12, each with
a Mobile Switching Center (MSC) 14 and an integrated Visitor
Location Register (VLR) 16 therein. The MSC 14 provides a circuit
switched connection of speech and signaling information between a
Mobile Station (MS) 20 and the PLMN 10. The MSC/VLR areas 12, in
turn, include a plurality of Location Areas (LA) 18, which are
defined as that part of a given MSC/VLR area 12 in which the MS 20
may move freely without having to send update location information
to the MSC 14 that controls the LA 18. Each LA 18 is divided into a
number of cells 22. The MS 20 is the physical equipment, e.g., a
car phone or other portable phone, used by mobile subscribers to
communicate with the cellular network 10, each other, and users
outside the subscribed network, both wireline and wireless.
The MSC 14 is in communication with at least one Base Station
Controller (BSC) 23, which, in turn, is in contact with at least
one Base Transceiver Station (BTS) 24. The BTS is the physical
equipment, illustrated for simplicity as a radio tower, that
provides radio coverage to the cell 22 for which it is responsible.
It should be understood that the BSC 23 may be connected to several
BTS's 24, and may be implemented as a stand-alone node or
integrated with the MSC 14. In either event, the BSC 23 and BTS 24
components, as a whole, are generally referred to as a Base Station
System (BSS) 25.
With further reference to FIG. 1, the PLMN Service Area or cellular
network 10 includes a Home Location Register (HLR) 26, which is a
database maintaining all subscriber information, e.g., user
profiles, current location information, International Mobile
Subscriber Identity (IMSI) numbers, and other administrative
information, for subscribers registered within that PLMN 10. The
HLR 26 may be co-located with a given MSC 14, integrated with the
MSC 14, or alternatively can service multiple MSCs 14, the latter
of which is illustrated in FIG. 1.
Determining the geographical position of an MS 20 within a cellular
network 10 has recently become important for a wide range of
applications. For example, location services (LCS) may be used by
transport and taxi companies to determine the location of their
vehicles. In addition, for emergency calls, e.g., 911 calls, the
exact location of the MS 20 may be extremely important to the
outcome of the emergency situation. Furthermore, LCS can be used to
determine the location of a stolen car, for the detection of home
zone calls, which are charged at a lower rate, for the detection of
hot spots for micro cells, or for the subscriber to determine, for
example, the nearest gas station, restaurant, or hospital, e.g.,
"Where am I" service.
As can be seen in FIG. 2 of the drawings, upon a network
positioning request for a particular target MS 20, the MSC 14
obtains, from the serving BTS 24 and BSC 23, a Timing Advance (TA)
value, which corresponds to the amount of time in advance that the
MS 20 must send a message in order for the serving BTS 24 to
receive it in the time slot allocated to that MS 20. The TA value,
in turn, provides location information regarding the MS 20
location. This is due to the fact that when a message is sent from
the MS 20 to the BTS 24, there is a propagation delay, which
depends upon the distance between the MS 20 and the BTS 24. The TA
values are expressed in bit periods, and can range from 0 to 63,
with each bit period corresponding to approximately 550 meters
between the MS 20 and the BTS 24.
This TA value is forwarded to a Serving Mobile Location Center
(SMLC) 270 for use in assisting the calculation of the geographical
location of the MS 20. It should be noted that the SMLC 270 can use
a number of different positioning mechanisms, including, but not
limited to, Time of Arrival (TOA), which is a network-based
positioning method, or Enhanced Observed Time Difference (E-OTD) or
Global Positioning System (GPS), which are both MS-based
positioning methods. After the SMLC 270 calculates the MS 20
location, this location can be sent to a Location Application (LA)
280 that requested the positioning. It should be noted that the
requesting LA 280 could be located within the MS 20 itself, within
the MSC 14 or could be an external node, such as an Intelligent
Network (IN) node. If the LA 280 is not within the MS 20 or within
the MSC 14, the location information is sent to the requesting LA
280 via the MSC 14 and a Gateway Mobile Location Center (GMLC)
290.
As mentioned above, two common types of MS-based positioning
methods are the E-OTD method and the GPS method. For the GPS
method, the MS 20 can have a Global Positioning System (GPS)
receiver built into it, which is used to obtain positioning data,
which is sent to the SMLC 270 to determine the location of the MS
20. For the E-OTD method, the MS 20 can collect positioning data
based on the Observed Time Difference (OTD) between the time a BTS
24 sends out a signal and the time the MS 20 receives the signal.
This time difference information can be sent to the SMLC 270 for
calculation of the location of the MS 20, or the MS 20 itself, with
knowledge of the location of the BTS 24, can determine it's
location. It should be noted that it is expected in the near future
for the GPS receiver within the MS 20 to be able to calculate the
MS 20 location.
By utilizing the E-OTD or GPS positioning method and implementing
the location calculation functionality within the MS 20 itself, it
is no longer necessary to have active two-way communication between
the MS 20 and the network 10, which advantageously reduces the
signaling traffic on the network 10. This is especially true for
the situation where the requesting LA 280 includes in the
positioning request an indication of the frequency and duration of
the positioning. Once the MS 20 receives the positioning request,
along with the duration and frequency information, the MS 20 can
continuously position itself without any further contact with the
network 10.
However, as a result of the lack of communication with the network
10, especially when the positioning request instructs the MS 20 to
position itself multiple times or for a certain period of time, the
network 10 may not be informed of the number and/or duration of the
location calculations performed by the MS 20. This type of
information may be useful to the network 10 for charging or
statistical purposes.
It is, therefore, an object of the present invention to require the
MS to notify the network of the number and/or duration of
positionings performed by the MS.
SUMMARY OF THE INVENTION
The present invention is directed to telecommunications systems and
methods for requiring a mobile station (MS) to notify the network
of the number and/or duration of positionings performed by the MS.
A service program or API (Application Program Interface), e.g.,
JAVA program, which is responsible for collecting information
regarding the requests for location information, is either included
in a Subscriber Identity Module (SIM) card, or other memory, of the
MS or downloaded to the SIM card in the MS. As a result of
performing a location calculation, the API within the MS initiates
a mobile originated reporting Short Message Service (SMS) or
Unstructured Supplementary Service Data (USSD) message to the
serving network, which includes a time stamp of the time and date
the positioning request was received, the number and/or duration of
the positioning and the final calculated location of the MS.
Alternatively, this information can be uploaded to the network
using a Wireless Application Part (WAP) interface. In addition, the
reporting message can be sent either on a per positioning request
basis or on a per selected reporting frequency basis, in which the
reporting frequency is determined by the network. If the reporting
message is sent on a reporting frequency basis, the information,
e.g., time stamp, duration and location, can be stored in the SIM
card until the reporting message is sent. Advantageously, by
notifying the network of the number and/or duration of positionings
that the MS performs, the network can ensure that there is not a
loss of extra revenue when MS's perform their own location
calculations.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosed invention will be described with reference to the
accompanying drawings, which show important sample embodiments of
the invention and which are incorporated in the specification
hereof by reference, wherein:
FIG. 1 is a block diagram of a conventional wireless
telecommunications system;
FIG. 2 is a block diagram illustrating a conventional sample
positioning of a mobile station within a cellular network;
FIG. 3 illustrates providing a serving mobile location center with
various terminal-based positioning methods that may be performed by
a particular mobile station;
FIG. 4 illustrates the reporting of positioning information related
to terminal-based calculated location information in accordance
with embodiments of the present invention;
FIG. 5 illustrates a sample positioning process in accordance with
embodiments of the present invention;
FIG. 6 shows steps in implementing the sample positioning process
shown in FIG. 5 of the drawings;
FIG. 7 illustrates a sample Global Positioning System (GPS)
positioning method in accordance with embodiments of the present
invention;
FIG. 8 shows steps in implementing the sample GPS positioning
method shown in FIG. 7 of the drawings;
FIG. 9 illustrates a sample Enhanced-Observed Time Difference
(E-OTD) positioning method in accordance with embodiments of the
present invention; and
FIG. 10 shows steps in implementing the sample E-OTD positioning
method shown in FIG. 9 of the drawings.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY
EMBODIMENTS
The numerous innovative teachings of the present application will
be described with particular reference to the presently preferred
exemplary embodiments. However, it should be understood that this
class of embodiments provides only a few examples of the many
advantageous uses of the innovative teachings herein. In general,
statements made in the specification of the present application do
not necessarily delimit any of the various claimed inventions.
Moreover, some statements may apply to some inventive features but
not to others.
With reference now to FIG. 3 of the drawings, when a positioning
request 285 for a particular target Mobile Station (MS) 20 is
received by a Serving Mobile Location Center (SMLC) 270 serving the
cell 22 within the Public Land Mobile Network (PLMN) 10 that the MS
300 is currently located in, the SMLC 270 must choose the optimum
positioning method available. Positioning methods can be
network-based, e.g., Timing Advance (TA) method, Time of Arrival
(TOA) method, or Angle of Arrival (AOA) method, or terminal-based,
e.g., Global Positioning System (GPS) method, Observed Time
Difference (OTD) method, or Enhanced OTD (E-OTD) method. In order
for the SMLC 270 to have knowledge of the terminal-based
positioning methods, this information must be sent to the SMLC 270
together with the positioning request 285. Therefore, the MS 20
positioning capabilities can be sent to a serving Mobile Switching
Center/Visitor Location Register (MSC/VLR) 14/16 when the MS 20
registers with the MSC/VLR 14/16.
For example, in GSM systems, the MS 20 positioning method
capabilities can be passed towards the MSC/VLR 14/16 with the
existing GSM message BSSMAP CLASSMARK UPDATE message 200, as is
understood in the art. Specifically, as discussed in co-pending
patent application Ser. No. 09/037,071 to Stephen Hayes et al.,
which is hereby incorporated by reference, the "classmark
information element 3" in the CLASSMARK UPDATE message 200 can be
extended to include MS 20 positioning capabilities 205. As is known
in the art, the CLASSMARK UPDATE message 200 typically describes
attributes of the MS 20, such as encryption capabilities, RF power
level supported and short message capability. For example, the MS
20 positioning methods can be sent towards the network 10 as part
of controlled early classmark sending, during dedicated mode, when
the MS 20 wishes to indicate to the MSC/VLR 14/16 a change of
positioning capabilities, after a BSSMAP CLASSMARK REQUEST message
from the MSC/VLR 14/16, in which case the MS 20 can send the
CLASSMARK UPDATE message 200, including the positioning
capabilities 205. Alternatively, the MS 20 can send a HANDOVER
REQUEST message (not shown), including the MS 20 positioning
capabilities 205, to the target BSC 23 via a Base Transceiver
Station (BTS) 24.
This positioning capability information 205 shall indicate to the
MSC/VLR 14/16 whether the MS 20 can support terminal-based
positioning, the type of terminal-based positioning methods
supported, and whether the MS 20 is capable of performing location
calculations based upon the positioning measurements that it
performed itself. Once the MSC/VLR 14/16 receives the
terminal-based positioning methods, this information can be sent to
the SMLC 270 for later use in determining the optimum positioning
method.
Thus, if the MS 20 has terminal-based positioning capabilities,
along with terminal-based location calculation abilities, when the
SMLC 270 receives the positioning request 285, the SMLC 270 can opt
to allow the MS 20 to both obtain positioning measurements and to
calculate it's own location based upon those positioning
measurements. However, as discussed hereinbefore, if the MS 20
obtains the positioning measurements and determines it's own
location, the active two-way communication normally involved in the
positioning process between the MS 20 and the network 10 is
eliminated, which reduces the ability of the network 10 to be
informed about the number and/or duration of the
positioning(s).
Therefore, as shown in FIG. 4 of the drawings, a reporting module
260, such as a service program or Application Program Interface
(API), e.g., JAVA program, which is responsible for collecting and
reporting to the network 10 information regarding the received
positioning requests 285, can be either included in a Subscriber
Identity Module (SIM) card 250, or other memory, of the MS 20 or
downloaded to the SIM card 250 in the MS 20. Alternatively, the
reporting module 260 can be included within or downloaded to the
SIM card 250 within a Universal Mobile Telecommunications System
(UMTS), which is a new type of MS 20.
The reporting module 260 can be downloaded to the MS 20, for
example, as a part of the Virtual Home Environment (VHE) of the
mobile subscriber associated with the MS 20, using a Mobile Station
Application Executory Environment (MexE) or SIMTOOL kit or a
Wireless Application Part (WAP) interface to a web server
containing the reporting module 260 software. The VHE defines a
system concept for personalized service portability across network
boundaries and between terminals. The MexE provides a standardized
execution environment in an MS 20 and provides the MS 20 with the
ability to negotiate it's supported capabilities with a MexE
service provider, which allows applications to be developed
independently of any MS 20 platform. On the other hand, the SIMTOOL
kit provides applications within the SIM card 250 with the ability
to interact and operate with any MS 20 that supports the specific
requirements of the applications.
Once the MS 20 with the reporting module 260 therein receives the
positioning request 285, which can include the number and/or
duration of the positioning(s) that the MS 20 must perform, the MS
20 begins to calculate its' own location. As is understood in the
art, for terminal-based location calculation methods, the cellular
network 10 serving the MS 20 sends to the MS 20 positioning
measurement information 210, e.g., BTS 24 coordinates information
broadcasted on the Broadcast Control Channel (BCCH) unencrypted to
the MS 20, along with other necessary information, depending upon
the positioning method used, regardless of the location of the MS
20. The MS 20 calculates it's own location in idle or dedicated
mode based upon its own positioning measurements 215, the
additional information 210 supplied by the network 10 and a
location calculation function within the MS 20.
Specifically, the location calculation within the MS 20 can be
carried out by utilizing a Positioning Measurement Module (PMM) 220
within the MS 20 for performing the positioning measurements 215
with the aid of information 210 from the network 10, which is sent
over interface I/f-a from a Transceiver (TRX) unit 240, and an
algorithm 225 specific to the positioning method used. Thereafter,
a Location Calculation Module (LCM) 230 within the MS 20 can
convert the positioning measurements 215 to location information
298 with the aid of the network information 210 and an algorithm
235 for performing the conversion.
When the PMM 220 obtains the positioning measurements 215, the PMM
220 sends the positioning measurements 215 to the LCM 230 within
the SIM card 250 over interface I/f-b. The LCM 230 uses these
positioning measurements 215 as well as the network information 210
and the positioning algorithm 235 to perform the conversion and
calculate the location 298, e.g., X, Y coordinates, of the MS
20.
As a result of performing a location calculation, the reporting
module 260 within the MS 20 initiates a mobile originated reporting
Short Message Service (SMS) or Unstructured Supplementary Service
Data (USSD) message 275 to the serving network 10, which includes a
time stamp 276 of the time and date the positioning request was
received, positioning information 277, such as the number and/or
duration of the positioning(s) and the final calculated MS 20
location 298. Alternatively, this reporting message 275 can be
uploaded to the network 10 using a Wireless Application Part (WAP)
interface. In addition, the reporting message 275 can be sent
either on a per positioning request 285 basis or on a per selected
reporting frequency 265 basis, in which the reporting frequency 265
is determined by the network 10 and included in the reporting
module 260. If the reporting message 275 is sent on a selected
reporting frequency 265 basis, the time stamp 276, positioning
information 277 and final calculated MS 20 location 298, can be
stored in a memory, such as a Random Access Memory (RAM) 245,
within the SIM card 250 until the reporting message 275 is
sent.
The reporting module 260 can transmit the SMS or USSD message 275
to the network 10 by passing the time stamp 276, positioning
information 277 and final calculated MS 20 location 298 to the TRX
unit 240 over interface I/f-c for transmission to the network 10.
In addition, it should be understood that the SIM card 250
preferably contains a central processing unit (CPU) 255 for
controlling the flow of information between the PMM 220, LCM 230,
RAM 245, reporting module 260 TRX unit and any internal LA 280.
Furthermore, in order to offer the reporting service seamlessly,
the platform executing the reporting module 260 described above
must be either an open platform or bilaterally agreed between the
home network 10 and a visiting network (not shown) if the MS 20 is
roaming.
A more complete understanding of aspects of the positioning process
involved in the present invention will now be described with
reference to FIG. 5 of the drawings, which will be described in
connection with the steps listed in FIG. 6 of the drawings.
Positioning of a particular target MS 20 typically begins by a
Location Application (LA) 280 (or location node 280) sending a
positioning request 285, which specifies the particular Mobile
Station Integrated Services Digital Network (MSISDN) number
associated with the particular target MS 20 to be positioned, to a
Gateway Mobile Location Center (GMLC) 290 within the Public Land
Mobile Network (PLMN) 10b of the LA 280 (step 600). In addition,
the positioning request 285 can include the duration and/or number
of positionings to be performed by the MS 20, as discussed
hereinbefore.
When the GMLC 290 receives the positioning request 285 (step 600),
the GMLC 290 sends a request for routing information (step 605),
e.g., the address of the serving MSC 14 within the PLMN 10a that
the MS 20 is currently located in, to the MS's Home Location
Register (HLR) 26, using the MS's 20 directory number as a global
title. The signaling network, e.g., the Signaling System #7 (SS7)
network (not shown), can perform a global title translation on the
MSISDN and route the request to the appropriate HLR 26 for the MS
20.
The HLR 26 checks its records to confirm that the MS 20 is
registered in the HLR 26 (step 610), and that routing information
for that MS 20 is available (step 615). If the MS 20 is not
registered in the HLR 26 (step 610) or the routing information is
not available (step 615), the positioning request 285 is rejected
(step 620) and the GMLC 290 sends a rejection message 295 to the
requesting LA 280 (step 625). However, if the MS 20 is registered
in the HLR 26 (step 610) and routing information for the MSC 14 is
available (step 615), the routing information, e.g., the MSC 14
address, is sent to the GMLC 290 (step 630). Using this MSC 14
address, the GMLC 290 transmits a MAP_PROVIDE_SUBSCRIBER_LOCATION
message, which contains the positioning request 285, to the serving
MSC 14 (step 635).
The MSC 14 verifies that the MS 20 allows positioning to be
performed (step 640), e.g., by checking privacy information, such
as a Subscriber Location Privacy Profile (SLPP), which is sent to
the Visitor Location Register (VLR) 16 associated with the serving
MSC 14 by the HLR 26. If the MS 20 does not allow positioning (step
640), the positioning request 285 is rejected (step 620) and a
rejection message 295 is sent to the LA 280 (step 625).
However, if the MS 20 does allow positioning (step 640), and the MS
20 is in idle mode (step 650), the VLR 16 performs paging and
authentication of the MS 20, along with ciphering of the
positioning data. This procedure provides the current cell 22 ID
and Timing Advance (TA) value for a serving Base Transceiver
Station (BTS) 24 in a BSSMAP Complete layer 3 message, which is
used to convey a paging response (step 655). However, if the MS 20
is in dedicated mode (step 650), e.g., involved in a call
connection, the MSC 14 obtains the current cell 22 ID from a
serving Base Station Controller (BSC) 23 (step 660) and sends a
BSSMAP TA request to the serving BSC 23 (step 665). The serving BSC
23 obtains a current TA value from the serving BTS 24 and returns
this current TA value in a BSSMAP TA response to the MSC 14 (step
670).
Upon receipt of the current cell 22 ID and TA value (step 655 or
670), the MSC 14 sends a MAP_PERFORM_LOCATION message, which
includes the current cell 22 ID and TA value, to the SMLC 270
associated with the MS's 20 current cell 22 location (step 675).
The SMLC 270 determines the positioning method to use, e.g., Time
of Arrival (TOA), Enhanced Observed Time Difference (E-OTD) or
Global Positioning System (GPS) (step 680). If the positioning is
successful, the MS 20 sends the location information 298 to the MSC
14, which, in turn, returns the location information 298 to the LA
280, via the GMLC 290. In addition, the reporting module 260, shown
in FIG. 4 of the drawings, transmits the reporting message 275 to
the serving network 10, which includes a time stamp 276 of the time
and date the positioning request was received, positioning
information 277, such as the number and/or duration of the
positioning and the final calculated MS 20 location 298.
In accordance with aspects of the present invention, two of the
terminal-based positioning methods will now be described. One of
these terminal-based positioning methods is the Global Positioning
System (GPS) method. GPS is a well-known technology used by many
military and civilian applications. It is based upon a
constellation of satellites launched by the U.S. government
beginning in 1978. The GPS satellites transmit the standard
positioning service (SPS) signal, which is available for civilian
applications on a 1575.42 MegaHertz carrier. Each satellite uses a
unique 1023-chip Gold code at a rate of 1.023 MegaHertz, such that
all codes repeat at 1 millisecond intervals.
Each satellite also transmits a unique 50 bit/second navigation
message containing parameters that allow GPS receivers on earth to
compute a precise position solution. The navigation message
includes a precise time reference as well as parameters that
precisely describe the orbital positions and clock corrections for
the satellites. In general, GPS receivers compute a position
solution by searching for all visible satellites, which can be
accomplished by correlating the received signal with replicas of
the respective Gold codes, demodulating the navigation message of
each visible satellite to obtain a time reference and orbital
position, computing a range estimate for each visible satellite
that includes the GPS receiver clock uncertainty, and, if at least
four satellites are visible, computing the GPS receiver position
and clock correction using the range estimate.
With reference now to FIG. 7 of the drawings, which will be
described in connection with the steps listed in FIG. 8 of the
drawings, when the SMLC 270 receives the cell 22 ID and TA value
(step 675 in FIG. 6 of the drawings) and decides to utilize the GPS
positioning method (steps 680 and 685 in FIGS. 6 and 8 of the
drawings), the SMLC 270 can determine the coordinates of the
serving BTS 24 (step 800), which preferably serves as the local
position estimate for the MS 20, and from this information, as
discussed in co-pending patent application Ser. No. 09/063,028 to
Christopher H. Kingdon et al., which is hereby incorporated by
reference, the SMLC 270 can determine a reference GPS receiver 700
(step 810), which is valid for the cell 22 that the MS 20 is
located in. Alternatively, the SMLC 270 can determine the correct
reference GPS receiver 700 (step 810) just from the cell 22 ID.
Multiple reference GPS receivers 700 and 705 are spaced throughout
the PLMN 10 in order to provide accurate assistance GPS data to GPS
receivers 710 within or attached to MS's 20. This data is used by
the built-in GPS receiver 710 to determine the location of the MS
20 within the PLMN 10. The data in each reference GPS receiver 700
and 705 is valid in a radius of up to 300 kilometers around the
reference GPS receiver 700 and 705 site (except for differential
correction information, which is only valid for a radius of up to
50 kilometers), and therefore, the correct reference GPS receiver
700 for the cell 22 that the MS 20 is in must be determined to
ensure the accuracy of the assistance GPS data. In addition, each
reference GPS receiver 700 and 705 must be placed such that the
antenna has an unobstructed view of the full sky.
After the SMLC 270 has determined the correct reference GPS
receiver 700 (step 810), the SMLC 240 obtains, from the reference
GPS receiver 700, the relevant assistance GPS data (step 820), such
as the identity of the visible satellites 720, the orbital
parameters of the satellites 720, clock corrections and
differential corrections. A current requirement is that this
assistance data be updated by the reference GPS receivers 700 and
705 about every thirty minutes (except for differential
corrections, which are updated about every five seconds).
Once the current assistance GPS data is obtained by the SMLC 270
(step 820), this information is forwarded to the built-in or
attached GPS receiver 720 within the MS 20 (step 830) via the
serving MSC 14, BSC 23 and BTS 24. This assistance data corresponds
to the network information 210 described in FIG. 4 of the drawings,
and is preferably broadcasted to the MS 20 over the BCCH (step
830). In addition, the built-in GPS receiver 270 encompasses at
least the PMM 220 and LCS 230 shown in FIG. 4 of the drawings.
Using this assistance GPS data, the built-in GPS receiver 720
within the MS 20 can obtain the GPS positioning measurements to
calculate its position 298 (step 840), e.g., latitude and
longitude, and transmit the calculated location information 298 to
the MSC 14 (step 850). Thereafter, the MSC 14 can forward the
location of the MS 20 to the GMLC 290 (step 860), which can, in
turn, forward the location information 298 to the requesting LA 280
(step 870). In addition to sending the location information 298 to
the network, the reporting module 260, shown in FIG. 4 of the
drawings, can initiate a reporting SMS or USSD message 275,
described in FIG. 4 of the drawings, towards the MSC 14 (step
880).
The second terminal-based positioning method is the E-OTD method.
With reference now to FIG. 9 of the drawings, which will be
described in connection with the steps listed in FIG. 10 of the
drawings, the E-OTD method is based upon measurements in the MS 20
of the Enhanced Observed Time Difference of arrival of bursts from
nearby pairs of BTS's 24a and 24b to the MS 20. To obtain accurate
triangulation of the MS 20 position, E-OTD measurements are needed
for at least three distinct pairs of geographically dispersed BTS's
24a and 24b, only one pair of which is shown in FIG. 9.
Thus, when the SMLC 270 receives the cell 22 ID and TA value (step
675 in FIG. 6) and decides to utilize the E-OTD positioning method
(steps 680 and 690 in FIG. 6 and FIG. 10), the SMLC 270 sends the
positioning request 285 to the MS 20 (step 100). The relevant BTS
24a and 24b coordinate information can be broadcast to the MS 20 on
the BCCH (not shown). The MS 20 performs the requested E-OTD
measurements (step 110) and computes an E-OTD location estimate 298
(step 120), as described hereinbefore in connection with FIG. 4 of
the drawings.
Thereafter, the MS 20 sends this calculated location information
298 to the MSC 14 (step 130). The MSC 14 forwards the location 298
of the MS 20 to the GMLC 290 (step 140), which can, in turn,
forward the location information 298 to the requesting LA 280 (step
150). In addition, along with sending the location 298 to the MSC
14, the reporting module 260, shown in FIG. 4, within the MS 20 can
initiate the reporting SMS or USSD message 275, described in FIG.
4, to the MSC 14 (step 160).
As will be recognized by those skilled in the art, the innovative
concepts described in the present application can be modified and
varied over a wide range of applications. Accordingly, the scope of
patented subject matter should not be limited to any of the
specific exemplary teachings discussed, but is instead defined by
the following claims.
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